In order to make the usage of mobile telephones in vehicles safer it is common to have hands free equipment stationary installed in the vehicle for audio input to and output from the telephone. The hands free equipment is provided with a connector for connecting a loudspeaker, a microphone and a power line to the telephone. In stationary hands free equipment the connector is often integrated with a docking unit with a holder fitting the telephone. The docking unit is usually mounted on the instrument panel of the vehicle within reach for the user, and when the mobile telephone unit is docked in the holder the telephone is controlled by means of the usual keypad and display on the telephone. There may also be some basic control keys integrated with or attached to the steering wheel. Some stationary hands free equipment is further coupled to an entertainment system or a vehicle information system of the vehicle, so that for example the audio output of a radio or a music player is switched off or silenced when an incoming telephone call is received.
There is also simpler hands free equipment such as a cable with an earphone, a microphone and a connector for connecting directly to an input/output socket of the telephone unit. There may also be a switch on the cable for basic control of the telephone such as answering or ending a call. Dialling and other handling of the telephone is done by means of the keypad and the screen of the telephone.
However, modern mobile telephones are small and for example in the vehicle environment it is often difficult to read the small screen of the telephone and to use the small keypad when handling the telephone and telephone calls. There are also other environments, circumstances or situations when it is unpractical or unsuitable to handle the telephone unit by means of the integrated keypad and screen.
Furthermore, there are technologies for coupling a stationary mounted hands free equipment wirelessly to a mobile telephone unit whereas the telephone might be left in a case or pocket and the user interface of the telephone may thus be out of hand.
There is therefore a need for a complementary user interface for mobile telephones.